An electric four-wheel drive (4WD) system, which is a four-wheeled system that allows all four wheels to receive torque, drives two rear wheels with an electric motor to supplement traction available to a front wheel drive vehicle, and may achieve 4WD and hybrid electric vehicle (HEV) functions.
A vehicle provided with the electric 4WD system includes an engine and a transmission for driving front wheels. A generator is configured to generate electrical energy from mechanical energy of the engine and supply the electrical energy to a battery. The electric 4WD system drives the rear wheels using the electric motor powered by the battery and a decelerator which decelerates the rotational speed of the motor. An output of the decelerator is transmitted to the rear wheels through a drive shaft. Here, the weight of the vehicle provided with the electric 4WD system can be reduced by eliminating, for example, a propeller shaft to reduce the fuel consumption and power loss in starting and driving of the vehicle.
The vehicle provided with the electric 4WD system may be provided with an active roll control apparatus controlling roll characteristic of a vehicle. The active roll control apparatus may adjust rigidity of stabilizer bars of front and rear wheels which operate an actuator using hydraulic pressure for enhancing turning stability of the vehicle.
The active roll control apparatus includes the actuator mounted to the stabilizer bars of the front and rear wheels. A hydraulic pressure pump supplies hydraulic pressure to the stabilizer bars, and a valve block supplies the hydraulic pressure to the actuator according to a control signal of an electronic control unit (ECU).
However, the electric 4WD system and the active roll control apparatus have a complicated structure, and marketability may be deteriorated due to the manufacturing cost and the weight.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.